Morphometric quantification of plasma cells in the intestinal mucosa of children. A comparative study between two sampling procedures.

In an attempt to obtain a sampling procedure of known accuracy for plasma cell quantification, applicable for routine analysis, we counted IgA, IgM and IgG producing cells in the lamina propria of the small intestine of six children by the method II of Aherne (1976), using two sampling procedures. In the first, we determined the number of cells in each one of 200 successive microscopic fields without specifying their localization in the mucosa. Proper tests upon this data showed that in order to estimate the number of IgA producing cells per mm3 of lamina propria with a confidence of 95% that the mean of the sample would not differ by more than 5% from the mean of the population, it would be necessary to count 850-900 microscopic fields. With a confidence of 90% that the two means cited will not differ between them by more than 10%, the number of fields to be counted would lie in the range of 150 to 200. In the second procedure we arbitrarily divided the mucosa into upper, middle and lower segments, identifying and counting the number of cells in each segment. Consistent results for the number of IgA, IgM and IgG-containing cells were obtained by averaging the data of sufficient number of counts of 30 fields: 10 in the upper segment, 10 in the middle segment and 10 in the lower segment. Means obtained by stratified counts of IgA producing cells in 60 microscopic fields, 20 in each segment, differed, in 93% of the samples, by no more than 10% from the mean derived from the counts of 200 successive fields. Stratified sampling also enabled us to detect a segmental variation which had not thus far been quantified. In all cases, it was observed that the numerical concentration of IgA producing cells was greater in the lower region than in the middle zone, while for both IgM and IgG cells the larger numbers occurred in the middle and lower segments. The lowest concentration of IgA, IgM and IgG cells occurred at the top of the villi.